If you have the thermo on Auto and at a comfortable, but not freezing, the compressor doesnt run as much. With the weather being what it is, its hard not to run the AC regardless of mpg (not a racing situation). For me personally, with my foot in the gas so much my mpg has become somewhat of a moot point. I figure I have to pay to play.

 

Yesterday I was playing with the computer and the A/C. I have done this before. The A/C cost me 2-3 MPG at highway speeds windows up. We had temps in the upper 90s so the A/C was a must. I think 15HP is a realistic number

 

I've never noticed a real difference in performance in my Cooper. In my old car, I found myself turning the AC off a lot to get more power, but I've never felt compelled to do that in this car. Next time I go up a big hill, I'll try switching it off halfway up and see what that does.

 

I notice the a/c power loss with my S taking off from a dead stop more than anything else, it just seems to labor. And my mpg loss is minimal, maybe 1-2 mpg at most.

 

Exactly the words my friend with his new 415 hp supercharged Roush Stage III 06 Mustang GT said last night....

 

AC ... another good reason to tune the ECU.

 

I think MINI has improved engine management over the years with regard to the air conditioning. My '02 Cooper was drastically effected by the A/C, where it is much less noticiable in my '06 Cooper.

This was one of many improvements I have noted 4 years of production has brought to the MINI.

 

At a track event ...you won't use AC on the track, as both windows come down

Turn it OFF just before you turn off the DSC on your way into the pit on !!!

 

it to be the same on the Mini...it's just intelligent engineering!

 

the engine will working so hard as AC on + 90F+ THE SUN on top.
You will see the big different when you drive the mc at night while the AC on.
The Sun will heat up the engine bay alot~

 

If off, it costs about 1.5 hp due to it's weight alone (23 lbs); and when on, as that MINI2 thread reveals, about 12 hp additionally...

 

AC is a HUGE drain on my 03 MCS's power. I only use it if my wife is in the car or on the freeway. However, moving to a 15% smaller supercharger pulley and getting the one-ball exhaust mod done makes the car actually drivable with the AC on.

 

I was wondering why the wide range of opinions, on the S especially. We had some saying little difference and some saying it was awful. I wondered if the year made a difference, and especially the lower 1st gear in the 05 and beyond.

Now I see a post form one who had a 02 and now a 06. Sounds like it's something they've improved. I for one don't notice a large difference with the A/C on in my 05 S.

As for those clever BMW engineers and their clever A/C cutout, be aware my 78 Subaru did the same. Of course it was just a mechanical switch next to the throttle linkage that broke the lead to the compressor at WOT. While ours is probably all in software, but the switch did the job!

 

I was quite surprised at how much the AC affects preformance. It is very noticeable, very. I almost never use it because of this. Of course, living by the beach one does not really need to use it either.

 

So, when racing, windows up with the heater at max?

 

 

hehe you would roast alive with the windows up and heater on

 

With temps in DC running 98-100 the last two days, I've also got to say the A/C is doing a fantastic job. Cold as heck and after a minute or two I've got to back it off a notch.

And again, the car's performance is only marginally effected. Not as much as other 4 bangers I've had. But, I also have a pulley. Perhaps that and the 05's lower gearing is helping?

I'm a happy and cool camper!

 

Ive never found it to be a huge power robber after my mods. It bothered me more when it was in stock form.After an intake exhaust and pulley and wires, I hardly notice it.They have been making the compressor shutoff at WOT for yrs.Not only BMW.
It seems to me with all of the mechanical devices that where once ran off of the engine that have now been converted to electric, they would come up with a motor and belt configuration or a direct drive motor setup for the ac compressor.Think about it,air compressor,fuel pumps,POWER STEERING PUMP!
I think it may only be a matter of time before they come up with one.Especialy with how small the engines have become and how effecient they are now days. I'm surprised they havent came up with one yet.